Toner applicator for magnetic printing system

ABSTRACT

For use in a magnetic printing system in which magnetic toner powder is applied to recorded areas of a magnetic surface for subsequent transfer to a writing surface, apparatus for applying toner powder to the recording surface and for retaining the toner in an enclosed environment to prevent contamination of the printing apparatus. A substantially closed toner supply is employed having a first section confronting a first portion of a recording surface at which powder is applied, and a second section confronting a second portion of the recording surface at which residual amounts of toner are removed. A transport mechanism is provided to convey material removed from the recording surface from the second section back to the first section to replenish the toner supply and may include conveyor apparatus operative to convey toner powder away from the imprinting mechanism.

. United States Patent [191 Ott et al.

'[111 3,825,936 145 July 23, 1974 1 [75] Inventors: Owen J. Ott', Brookfield Center;

David W. Ginn, Newton; Lester F. Miller, Jr B'ethel, all of Conn.

' [73] Assignee: Data Interface, Inc., Danbury,

Conn.

22 'Filed: May24, 1972 1211 A l. No.: 256,417

[52] I US. Cl. 346/74 MP, 346/74 ES, 117/17.5, 118/637 "[51 Intel G01d 15/00, G01d15/l2,

58 Field at sales... 3 16/74 MP, 7412s; 118/637;

Royka Benson 118/637 Primary Examiner-Paul J. Henon Assistant Examiner-James D. Thomas Attorney, Agent, or Firm-Weingarten, Maxham &

Schurgin [57] ABSTRACT For use in a magnetic printing system in which magnetic toner powder is applied to recorded areas of a magnetic surface for subsequent transfer to a writing surface, apparatus for applying toner powder to the 1 recording surface and for retaining the toner in an enclosed environment to prevent contamination of the printing apparatus. A substantially closedtoner supply.

is employed having a first section confronting a first portion of a recording surface at which powder is applied, and a second section confronting a second portion of the recording surface at which residual amounts of toner are'remove'd. A transport mechanism is provided to convey material removed from, the recording surface from the second sectionrback to the first section to replenish thetoner supply and may include conveyor apparatus operative to convey toner powder away from the imprinting mechanism.

8 Claims, 6 Drawing Figures I I [56] Y References Cited UNITED STATES PATENT v 3,032,009 5/1'962 Magnusson .1 118/637 3,043,685 7/1962 -Rosenthal.' 96/1 3,142,840 7/1964 Smith 346/74 3,161,544 12/17964 Berry 118/637 3,283,334 l1/1966, K utik- 346/74 ES 3,355,743 ll/1.967 Cappss... 346/74 ES 3,572,288 3/1971 Turner" 118/637 3,633,545 1/1972 Samaniego 118/637- 5 3,641,585 2/1972 Hudges .346/74MP 1 3,664,299 5/1972 Shaler et al .LQ 1'18/637 3,667,427 6/1972 Hewitt, 118/637 PATENTEDJURBISH SHEET 30F 3 TONER APPLICATOR FOR MAGNETIC PRINTING SYSTEM FIELD OF THE INVENTION This invention relates to magnetic printing systems andmore particularly to .apparatus for the efficient handling of magnetic toner particles in a magnetic printing system.

BACKGROUND OF THE INVENTION A magnetic printingsystem is the subject of copending application Ser. No. 138,924, filed Apr. 30, 1971,

-. now US. Pat,No. 3,735,416 andassigned to the assignee of the present invention, wherein characters or other data to be printed are formed'as selected magnetic image patterns on a recording surface. A magnetic toner is, applied to the recording surface and adheres to the recorded patterns, the adhered toner then being transferred from the recorded surface to a writing surface to form a printed image thereon. Typically,

the recording surface is part of an endless loop of mag-.

netic recording tape which is disposed in a path having associated therewith a magnetic recording head and a magnetic erase head. The tape is magnetized by the recording head in accordance-with data to be printed, and magnetic toner powder is applied to the tape for retention by the recorded areas by an applicator which can includev a rotating brush for sweeping toner particles onto the recording surface. The tape is moved to a printing position where the toner adhered to the recorded areas is transferred to a confronting writing surface, the transferred toner usually being fixed by application of heat. After printing, the tape is movedto an erase position where previously recorded data is erased -cording surface and removal of residualpowder from erased portions of the recording surface.

SUMMARY or THE INVENTION In accordance with the present invention, apparatus is provided for use in a magnetic printing system which substantially eliminates contamination of the printing mechanism which can result in smudging of the writing surface and clogging of machine elements. A substantially closed toner reservoir system is provided containing a supply of toner powder and having first and second sectionswhich respectively confront first and second portions of the recording surface. The first section includes means such as a rotary brush assembly for applying toner powder to the recording surface, while the second section includes means for removal of residual amounts of toner from the recording surface after transfer of printed images onto a writing surface. Toner powder in the second section is continuously conveyed back to the first section to replenish the supply of toner therein, and conveyor apparatus can also be provided to transport toner away from the working elements of DESCRIPTION OF THE DRAWING I The i..vention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a pictorial view, partly cut-away, of a magnetic printing system embodying the invention; I

FIG. 2 is a pictorial view of the motor and driveapparatus employed in the embodiment of FIG. 1

FIG. 3 is a pictorial view, partly cut-away, of the transmission assembly of the embodiment of FIG. 1 and which is coupled to the drive apparatus of FIG. 2;

FIG. 4-is an elevation view of a mission assembly of FIG. 3;

FIG. 5 is a cut-away pictorial .view of an alternative embodiment of the invention; and

FIG. 6 is a cut-away pictorial view of a toner applicator embodiment in the invention.

DETAILED DESCRIPTION OF THE INVENTION A magnetic printing system embodying the invention is depictedin FIG. 1 and includes a magnetic recording tape 10 disposed in a generally rectangular loop by rollers 12a-12d, the tape 10 being driven about its closed path by a capstan l4and associated pinch roller 15 disposed in a position between rollers 12a and 12b, and which is part of the tape transport apparatus to be described. A magnetic' recording head 16 is disposed adjacent capstan 14 in confronting relationship to the inner surface of tape 10-and is connected to recording circuitry (not shown) well known in the art for impress ingdata onto the tapein the form of a pattern of magnetic images. A magnetic erase head '18 is disposed in the position illustrated near roller 12d and adjacent the upper surface of tape 10 and is connected to well known circuitry (not shown) for erasing the magnetic images on the tape. An elongated cylindrical drum 20 is disposed in the illustrated embodiment within and generally parallel to the tape loop and is supported for rotation by respec: tive bearings 22 and 24 provided at respective ends of the drum and which cooperate with matingsurfaces of the support structure. A raised bridge 26is-formed in a helical path across the cylindrical surface of drum 20 and serves as a camming surface to transfer data from the magnetic tape 10 onto an associated writing surface 28, in a manner to be explained. I

The drum 20 is disposed between and rotatable with respect to a first housing 30 located adjacent record head 16, and a second housing 32 confronting erase head 18, which respectively serve as a supply reservoir for toner powder to be applied to the magnetic tape 10 and a reservoir for the collection of toner removed a from the tape after printing. According to the invention, apparatus is provided in association with the housings 30 and 32 for transporting toner removed from the tape back to the supply reservoir and also for mainte- .nance of the toner powder at positions removed from the other elements of the printing'system to prevent fouling of the system and smudging of the writing surface.

A tube 34 is disposed coaxially within drum 20 and extends beyond the extremities thereof into respective housings 30 and 32. The tube 34 preferably extends alportion of the tran smost to the end wall of housing 30 and partially into housing 32. An elongated helical element 36 such as a wire spring is disposed throughout the length of tube 34 and extends beyond an end of tube 34 substantially into housing 32. The spring 36 is dimensioned to engage the inner surface of tube 34 and to rotate therewith to serve as a worm conveyor for transport of toner from housing 32 to housing 30. A second helical element or spring 38, of opposite pitch to that of spring 36, is dis- .posedaround the end of tube 34 extending within housing 32 and is engaged thereby and extends across the width of this housing. A worm 40 is provided around the end of tube 34 extending within housing 30 and is of a pitch the same asthat of spring 36. The drum 20, tube 34, springs 36 and 38 and worm 40 are constructed as an integral structure rotatable by the transport apparatus. A

The spring 38 is of a pitch to provide, upon rotation of drum 20 in a predetermined direction, conveyance of toner removed from the surface of tape confronting housing 32 away from bearing 24 and drum 20. The worm 40 similarly provides conveyance of toner within housing 30 away from the confronting end of drum and the associated bearing 22. Duringoperation of the printing apparatus, therefore, toner powder is maintained in respective housings at positions removed from the printing surfaces to prevent smudging of the writing surface and to also prevent contamination of machine elements.

The spring 36 which extends throughout the length of drum 20 between housings 30 and 32 is operative upon rotation of drum 20 to cause conveyance of toner powder in housing 32 removed from the tape surface, through the drum and into housing 30, thereby to replenish the supply of toner powder in housing 30. The exposed portion of spring 36 within housing 32 collects toner powder therein for conveyance into tube 34 and thence to housing 30. The rotation of the portion of spring 36within housing 30 can also cause agitation of the toner. contained therein to minimize any tendency of the toner powder to compact and to maintain a more uniform dispersion of powder for applicationof toner particles by brush 42 onto the recording surface of tape 10.,An elongated flat brush 37 is disposed in stationary position within spring 36 and is supported with the bristles in contact with the-inner surface of spring 36. The brush 37 is typically mounted by its ends on respective walls of housings 30-and 32, and serves to prevent compaction of toner powder as it is conveyed by spring 36 to housing 30.

A cylindrical brush 42 is provided in engagement with an extension of tube 34 within housing 30 and is adapted for rotation therewith to apply toner to the confronting surface of tape 10. The brush 42 is dimensioned and positioned to be immediately adjacent an aperture 44 provided in the upper surface of housing 30, tape 10 being transported across this aperture to receive toner powder by action of brush 42. A cover plate 46 is provided along the length of drum 20 and includes end portionsaftixed to respective sections 30 and 32. Plate 46 serves as a platen to maintain the writing surface 28 in position for transfer of printed data thereto from the magnetic tape 10 by action of cam 26. A resilient pad 48 can be provided in the surface of plate 46 confronting drum 20 to serve as a resilient platen against which the tape and writing surface are urged to affect image transfer from the tape to the writing surface. A pair of doctor blades 50 are provided at the upper portion of section 32 in a position transverse to the axis of tape 10 and on respective sides of erase head 18. Each of these blades has an upper edge in wiping contact with the confronting tape surface to remove toner from the tape as the magnetic images thereon are being erased by operation of the magnetic erase head 18.

The tape is driven by an electric motor acting through a belt and gear drive coupled to the tape capstan l4 and drum 20. The drive mechanism is shown more particularly in FIGS. 2-4 and includes a pulley 62 carried by motor shaft 64 and over which a drive belt 66 is disposed. The belt is also carried by a pulley 68 affixed to shaft 70 which also has a worm gear 72 provided thereon, and'a pulley 73 carried by shaft 75. A pulley 74 is coupled by a slip clutch 76 to shaft 78 which carries tape capstan 14. A stop plate 80 is provided on the capstan side of clutch 76 and is cooperative with a pawl 82 pivotally disposed on a support plate 84 and having the distal end thereof adapted to engage the stop plate.

The worm gear 72 is in driving relationship with pinion gear 86 which is affixed to a shaft 88. The shaft 88 is also affixed to a gear 90 meshing with gear 92 which, in turn, engages the gear 94 provided on the end of drum 20 adjacent housing 30. The shaft 88 is journaled through plate 84 and has an end affixed to a cam 96 which is cooperatively arranged with respect to pawl 82. The opposite end of shaft 88 also carries a cam 98 which is operative to energize the paper feed mechanism, as will be described. A gear 100 is meshing relationship with gear 90 is carried by a shaft 102 which is part of the paper feed mechanism.

During operation, the drum 20 and associated helical ridge 26 is in continuous rotation at a uniform speed. The tape 10 is caused to move about its closed path at a uniform rate during the recording of magnetic images thereon, and after a line of information is recorded the tape is stopped to permit transfer of ridge 26 which traverses the length of stationary tape to transfer the recorded patterns onto the confronting surface of paper 28. The paper web is stopped during this transfer phase and is then stepped to a subsequent line position for receipt of the next line of printing.

Referring to FIGS. 2 through 4, the drum 20 is driven in uniform rotary motion by means of gears 94, 92, 90 and 86, to which power is provided by pinion 72 driven by belt 66 coupled to motor 60. The tape 10 is driven by capstan 14 coupled via clutch 76 to the drive motor 60. The cam 96 carried by shaft 88 includes a raised portion 97 which extends along a major portion of the periphery of the cam, and a recessed portion 99. The cam 96 is cooperative with pawl 82 which is pivotally affixed to a support plate 84 of the drive assembly housing. The raised portion 97 of cam 96 is operative to maintain pawl 82 in its raised position, as shown in dotted outline in FIG. 4, to permit the rotation of slip clutch 76, and corresponding rotation of tape capstan 14.

During engagement of the recessed portion 99 of cam 96 with the confronting surface of pawl 82, the pawl is maintained in its lower position, as shown in solid outline in FIG. 4, to serve as a stop for raised plate 80 affixed to slip clutch 76. The engagement of plate 80 by pawl 82 prevents rotation of shaft 78 and tape capstan 14 causing tape motion to cease during an inc f terval defined by-the length of recessed portion 99,at

which time tonerpowder applied to the recorded areas of the recording surface are transferred to the writing surface of paper 28. The timing provided by cam 96 I and its associated elements is such to stop the motion 7 of tape 10 for an interval necessary to-perrnit ridge 26 l. of drum to traverse the length of the tape to print a line of' characters or other data onto the writing surface. In a typical embodiment, the helical ridge 26 extends over approximately one-fourth of the circumferential surface of drum 20, and thus approximately three-fourths of a rotational cycle of drum 20 is available for erasingthe printed portions of the tape, recording a newline of data and applying toner powder to the recorded areas for a subsequent printing cycle.

and 118 to a position at which sections of paper can be removed from the web after being printed. The paper is engaged betweenrollers 116 and 118 and is driven in the directionof arrows 120 upon rotation of these drive rollers.

The roller 118 is affixed to a pulley 122 driven by abelt 124 coupled to a pulley 126 which is carriedby shaft 102 drivenby gear 100. An arm 128'is pivotally disposed on shaft 102 and includes on an end thereof a pivotable roller 130 operative'to engage belt 124 I under the influence of a spring-132 connected between a pin 134 affixed to arm 128 and a support 136. In the position illustrated, the belt 124 is in driving relationship with pulley 122 to cause rotation of rollers 1 18 and 116. and consequent movement of paper. A solenoid 140 is provided having a-shaft operative to engage pin 134, and upon actuation, such as by a switch operated by cam 98, to cause movement of roller 130 out of engagement with belt 124 to'st'op paper feeding.

Thesp'ring 38 and worm gear 40 employed in the above embodiment to convey toner powder away from machine elements need not be present in all instances, and an alternative embodiment of the invention without these conveyors is shown in FIG. 5. Toner is con veyed between housing 150 and 152 by means of a helical spring 154 disposed within tube 156 which extends between the housings. An erase head 18 and blades 50 are provided in association with housing 150, as in the above embodiment. The tube 156 supports a cylindrical drum and transfer cam as in the embodiment described above; The housing 150 has a bottom'surface 158 which is raised from the lowermost portionof the the floor of housing 152 for collection by applicator brush 164.

inner surface of tube 156 such that toner powder on surface 158 is conveyed over the step 160 onto the conveyor spring 154 for transport to the supply housing 152. The end of spring 154 within housing is slightly tapered to ride over the step 160. An elongated stationary brush 162 is supported throughout the length of spring 154, with the bristles thereof in engagement with the inner surface of spring 154 to wipe toner from thissurface as the spring rotates. The spring 154 extends almost to the end wall of housing 152 and toner powder conveyed to this housing is deposited on The toner applicator is shown in FIG. 6 and includes brush 164 carried by tube 156. The brush confrontsa rectangular opening 44 across which the magnetic tape is conveyed, and a plate 166 is provided having an edge 168 disposed in engagement with the bristle ends of the brush for the purpose of snapping or flicking the bristles as they move past edge 168 to cause a stream of toner particles to be propelled through aperture 44 onto the recording surface of the confronting tape.

Various modifications and alternative implementations will occur to those versed in the art without de parting from the spirit and true scope of the invention. Accordingly,- it is not intended to limit the invention by what has been particularly shown and described except as indicated in the appended claims.

What is claimed is: I 1. A magnetic printing system comprising: a magnetic recording tape;

tape transport means adapted to move said recording tape in a predetermined path; g magnetic recording means disposed in operative association with said tape for recording data thereon representing information to be printed; magnetic erasing means disposed in operativeassociation with said recording tape for erasing data recorded thereon; a a a data receiving sheet having a portion thereof disposed in confronting relation with a'portion of said recording tape; v a sheet transporting means for moving [said data receiving sheet in a predetermined path; toner apparatus disposed in operative relation to said tape and having a first housing confronting a first portion of said tape at which magnetic toner powder contained in said first housing is applied to re-- corded areas of said tape, and a second housing 1 areas of said tape surface previously recorded by I said magnetic recording means;

transfer means operative after application of toner to recorded areas of said tape to urge the confronting portions of said tape and said data receiving sheet into engagement, thereby to transfer the toner on the recorded areas of said tape onto confronting portions of said sheet;

means in said second housing and operative after transfer of data from recorded areas of said tape onto said data receiving sheet to remove toner from said tape surface; and a an elongated conveyor means disposed between said first housing and said second housing and including a cylindrical tube disposed between said housings andhaving end portions extending into said respective housings, and a helical element disposed within and in engagement with the inner surface of said cylindrical tube throughout the length thereof and having anend portion extending beyond the confronting end of said tube and into said second housing, said tubev and helical element being rotatable to convey toner in said second housing removed from said tape surface to said first housing to replenish the tonersupply therein. i

2. A system according to claim 1 wherein said elongated conveyor means includes an elongated brush member disposed in stationary position within said helical element with the bristles of said brush member in contact with the confronting surface of said element to prevent compaction of said toner powder.

3. A- magnetic printing system comprising:

a magnetic recording tape;

tape transport means adapted to move said recording tape in a predetermined path;

magnetic recording means disposed in operative association with said tape for recording data thereon representing information to be printed;

magnetic erasing means disposed in operative association with said recording tape for erasing data recorded thereon;

a data receiving sheet having a portion thereof disposed in confronting relation with a portion of said recording tape;

sheet transporting means for moving said data receiving sheet in a predetermined path;

toner apparatus disposed inoperative relation to said tape and having a first housing confronting a first portion of said tape at which magnetic toner powder contained in said first housing is applied to recorded areas of said tape, and a second housing confronting a second portion of said tape at which magnetic images are erased and residual amounts of toner removed from the tape surface for collection in said second housing, said toner apparatus including: v

means disposed in said first housing for applying toner powder contained therein onto recorded areas of said tape surface previously recorded by said magnetic recording means;

transfer means operative after application of toner to recorded areas of said tape to urge the confronting portions of said tape and said data receiving sheet into engagement, thereby to transfer the toner on the recorded areas of said tape onto confronting portions of said sheet;

said transfer means including an elongated drum rotatable about its axis and disposed between said first and second housings and having a transfer cam on the outer surface of said drum operative upon rotation of said drum about its axis to urge the confronting portions of said tape and said sheet into engagement in a sequential sweep along a length of said tape;

means in said second housing and operative after transfer of data from recorded areas of said tape onto said data receiving sheet to remove toner from said tape surface; and

an elongated conveyor means disposed between said first housing and said second housing and including a helical worm conveyor disposed coaxially throughout the length of said drum and having end portions which extend into said respective first and second housings to convey toner in said second housing to said first housing.

4. A system according to claim 3 further including:

first conveyor apparatus disposed in said first housing and operative to maintain said toner at a position away from said transfer means; and

second conveyor means disposed in said second housing and operative to maintain toner at a position away from said transfer means.

5. A magnetic printing system comprising:

a magnetic recording tape;

tape transport means for moving said recording tape along a predetermined path;

magnetic recording means disposed in operative association with said tape at a first position for recording data thereon representing information to be printed;

means disposed in operative association with said tape at a second position for erasing data recorded thereon;

a data receiving sheet having a portion disposed in confronting relation with a portion of said recording tape;

sheet transporting means for moving said data receiving sheet in a predetermined path;

a first housing confronting a first portion of said tape and having toner applying apparatus therein operative to apply magnetic toner powder to recorded areas of said tape;

a second housing confronting said tape at said second position having said erasing means and including means for engaging confronting portions of the recording surface of said tape for removing toner from said tape surface for collection in said second housing;

an elongated drum rotatably disposed between said first and second housings and having a ridge helically disposed and upstanding from the circumferential surface of said drum and operative upon rotation of said drum to urge confronting portions of said tape and said sheet into engagement in a sequential sweep along a length of said tape, thereby to transfer toner on the recorded areas of said tape onto the confronting surface of said sheet; and

an elongated helical conveyor disposed throughout the length of a coaxial opening in said drum, said helical conveyor having end portions which extend substantially within said respective first and second housings, and said helical conveyor being operative during rotation of said drum to convey toner in said second housing removed from said tape to said first housing to replenish the toner supply therein.

6. A system according to claim 5 wherein said first housing includes:

toner applying apparatus having a closed reservoir containing a supply of toner powder and an aperture confronting the recording surface of said tape;

at said second housing for engaging said confronting portions of said recording surface includes at least one 9 10 doctor blade having an edge engaging said recording the floor of said second housing being raised from the surface to remove toner powder therefrom. bottom portion of the inner surface of said'tube;

8. A system according to claim wherein said helical the end of said helical element in said second housing conveyor includes a cylindrical tube extending between being operative to transport toner through said said first and second housings and a helical element 5 tube to said first housing. supported by the inner surface of said tube; 

1. A magnetic printing system comprising: a magnetic recording tape; tape transport means adapted to move said recording tape in a predetermined path; magnetic recording means disposed in operative associAtion with said tape for recording data thereon representing information to be printed; magnetic erasing means disposed in operative association with said recording tape for erasing data recorded thereon; a data receiving sheet having a portion thereof disposed in confronting relation with a portion of said recording tape; sheet transporting means for moving said data receiving sheet in a predetermined path; toner apparatus disposed in operative relation to said tape and having a first housing confronting a first portion of said tape at which magnetic toner powder contained in said first housing is applied to recorded areas of said tape, and a second housing confronting a second portion of said tape at which magnetic images are erased and residual amounts of toner removed from the tape surface for collection in said second housing, said toner apparatus including: means disposed in said first housing for applying toner powder contained therein onto recorded areas of said tape surface previously recorded by said magnetic recording means; transfer means operative after application of toner to recorded areas of said tape to urge the confronting portions of said tape and said data receiving sheet into engagement, thereby to transfer the toner on the recorded areas of said tape onto confronting portions of said sheet; means in said second housing and operative after transfer of data from recorded areas of said tape onto said data receiving sheet to remove toner from said tape surface; and an elongated conveyor means disposed between said first housing and said second housing and including a cylindrical tube disposed between said housings and having end portions extending into said respective housings, and a helical element disposed within and in engagement with the inner surface of said cylindrical tube throughout the length thereof and having an end portion extending beyond the confronting end of said tube and into said second housing, said tube and helical element being rotatable to convey toner in said second housing removed from said tape surface to said first housing to replenish the toner supply therein.
 2. A system according to claim 1 wherein said elongated conveyor means includes an elongated brush member disposed in stationary position within said helical element with the bristles of said brush member in contact with the confronting surface of said element to prevent compaction of said toner powder.
 3. A magnetic printing system comprising: a magnetic recording tape; tape transport means adapted to move said recording tape in a predetermined path; magnetic recording means disposed in operative association with said tape for recording data thereon representing information to be printed; magnetic erasing means disposed in operative association with said recording tape for erasing data recorded thereon; a data receiving sheet having a portion thereof disposed in confronting relation with a portion of said recording tape; sheet transporting means for moving said data receiving sheet in a predetermined path; toner apparatus disposed in operative relation to said tape and having a first housing confronting a first portion of said tape at which magnetic toner powder contained in said first housing is applied to recorded areas of said tape, and a second housing confronting a second portion of said tape at which magnetic images are erased and residual amounts of toner removed from the tape surface for collection in said second housing, said toner apparatus including: means disposed in said first housing for applying toner powder contained therein onto recorded areas of said tape surface previously recorded by said magnetic recording means; transfer means operative after application of toner to recorded areas of said tape to urge the confronting portions of said tape and said data receiving sheet into engagement, thereby to transfer the toner on the recorded areas of said tape onto confrontiNg portions of said sheet; said transfer means including an elongated drum rotatable about its axis and disposed between said first and second housings and having a transfer cam on the outer surface of said drum operative upon rotation of said drum about its axis to urge the confronting portions of said tape and said sheet into engagement in a sequential sweep along a length of said tape; means in said second housing and operative after transfer of data from recorded areas of said tape onto said data receiving sheet to remove toner from said tape surface; and an elongated conveyor means disposed between said first housing and said second housing and including a helical worm conveyor disposed coaxially throughout the length of said drum and having end portions which extend into said respective first and second housings to convey toner in said second housing to said first housing.
 4. A system according to claim 3 further including: first conveyor apparatus disposed in said first housing and operative to maintain said toner at a position away from said transfer means; and second conveyor means disposed in said second housing and operative to maintain toner at a position away from said transfer means.
 5. A magnetic printing system comprising: a magnetic recording tape; tape transport means for moving said recording tape along a predetermined path; magnetic recording means disposed in operative association with said tape at a first position for recording data thereon representing information to be printed; means disposed in operative association with said tape at a second position for erasing data recorded thereon; a data receiving sheet having a portion disposed in confronting relation with a portion of said recording tape; sheet transporting means for moving said data receiving sheet in a predetermined path; a first housing confronting a first portion of said tape and having toner applying apparatus therein operative to apply magnetic toner powder to recorded areas of said tape; a second housing confronting said tape at said second position having said erasing means and including means for engaging confronting portions of the recording surface of said tape for removing toner from said tape surface for collection in said second housing; an elongated drum rotatably disposed between said first and second housings and having a ridge helically disposed and upstanding from the circumferential surface of said drum and operative upon rotation of said drum to urge confronting portions of said tape and said sheet into engagement in a sequential sweep along a length of said tape, thereby to transfer toner on the recorded areas of said tape onto the confronting surface of said sheet; and an elongated helical conveyor disposed throughout the length of a coaxial opening in said drum, said helical conveyor having end portions which extend substantially within said respective first and second housings, and said helical conveyor being operative during rotation of said drum to convey toner in said second housing removed from said tape to said first housing to replenish the toner supply therein.
 6. A system according to claim 5 wherein said first housing includes: toner applying apparatus having a closed reservoir containing a supply of toner powder and an aperture confronting the recording surface of said tape; a brush rotatable with said elongated drum and operative to convey toner from said closed reservoir through said aperture; and an element supported in said first housing with an edge engaging the ends of the bristles of said rotatable brush and operative to snap said bristle ends to propel toner powder through said aperture onto said recording surface.
 7. A system according to claim 6 wherein said means at said second housing for engaging said confronting portions of said recording surface includes at least one doctor blade having an edge engaging said recording surface to rEmove toner powder therefrom.
 8. A system according to claim 5 wherein said helical conveyor includes a cylindrical tube extending between said first and second housings and a helical element supported by the inner surface of said tube; the floor of said second housing being raised from the bottom portion of the inner surface of said tube; the end of said helical element in said second housing being operative to transport toner through said tube to said first housing. 